A known ignition interlock mechanism for a column-mounted shift control assembly is disclosed in Dzioba U.S. Pat. No. 4,821,605. This mechanism includes a latch plate pivotally mounted on an end of an arcuate shaped detent plate. The latch plate has a locking surface which is selectively positioned via the interaction of a key cylinder slot, a lock pin, a ramped plunger, and a cable to prevent removal of an operator lever positioning arm from the Park position prior to the key cylinder being unlocked. The latch plate also includes a positioning surface which, when engaged by the positioning arm upon its return to Park position, will pivot the latch plate to thereby move the plunger and permit the lock pin to leave the key cylinder slot and permit the key to be returned to its lock and remove position.
A further known ignition interlock mechanism for a column-mounted shift control assembly is disclosed in Snell et al U.S. Pat. No. 5,299,470. This mechanism cooperates with the terminal end of the shift handle to prevent its movement out of the Park detent position unless the ignition switch key is turned on, and further prevents the ignition switch from being turned on, and further prevents the ignition switch from being turned back to Lock unless the terminal end is in Park position, thus preventing key extraction.
A still further ignition interlock mechanism for a column-mounted shift control assembly is disclosed in Snell patent application, Ser. No. 08/343,052, filed on Nov. 21, 1994, now U.S. Pat. No. 5,511,641, issued Apr. 30, 1996. This mechanism includes a disc arrangement formed on the end of the brake lever opposite the brake pedal for receiving the brake cable from a spring biased blocker member for serving to prevent removal of the blocker member from the shift control lever in its park position prior to the depression of the brake pedal.